Management of Posterior Fossa Medulloblastoma in Adults

Abstract

Background: Medulloblastoma is a malignant tumor of the cerebellum that occurs predominantly in children. It is rare in
adults and accounts for less than 1 % of all adult primary brain tumors.
Objective: This study was done to study clinical picture, radiological findings, to evaluate the surgical outcome and to
assess the effects of postoperative adjuvant therapy in 12 adult patients who had posterior fossa medulloblastoma
Methods: This prospective study was carried out on consecutive 12 adult patients who had posterior fossa
medulloblastoma. This study was done in Alexandria hospitals over a period of 3 years starting from March 2006 to March
2009. The male to female ratio was 2 to 1(8 males and 4 females) and their ages ranged from 19 to 51 years with mean age
of 33, 8 years. Headache was the most frequent symptom (93,5% of patients). As regards the clinical presentation,
manifestations of increased intracranial pressure was found in 10 patients (83,3%), cerebellar dysfunction in 8
patients (66,6%), cranial nerve deficits in half of the cases. The tumour was hemispheric in 10 cases (6 lateral and
4 paramedian) and vermian in 2 cases. All patients had preoperative craniospinal MRI examination. No distant or
spinal metastases were detected in our patients at the time of diagnosis. All cases underwent surgery in the form of
resection of the tumour followed by postoperative craniospinal irradiation. Also two patients with recurrence and
metastases received ad-juvant craniospinal radiotherapy and systemic chemotherapy. Mean postoperative follow up
period was 24 months, including both clinical and MRI examination.
Results: There were no operative mortality, and surgery did not provoke any permanent neurological aggravation. Postoperative
MRI studies showed complete tumour resection was achieved in 9 patients (75%). After initial treatment only two
patients relapsed in the posterior fossa after one and half year. Recurrence was probably related to incomplete tumor
resection and long delay in initiating radiotherapy (3 months after operation). Two of the patients that received adjuvant
treatment died: one from distant metastasis and one from recurrent disease. Ten patients remained alive and disease-free
with Karnofsky performance status ranging from 80 to100.
Conclusion: Adult medulloblastoma was predominant in males and the majority of patients had hemispheric cerebellar
tumors. Adults are more likely to have heterogeneous cerebellar tumours on MRI, and this is thought to be related to the greater
prevalence of desmoplastic variant in adulthood. Long-term survival was not uncommon. The outcome depends on the site
of the tumour with better results obtained in cases with lateral hemispherical tumour that facilitate its complete surgical
resection and good irradiation planning.

Key words: Adult Medulloblastoma; Posterior Fossa; Craniospinal Irradiation; Desmoplastic Type.